Variable offset positioning antenna array for enhanced guidance of automated guided vehicles (AGVS)

ABSTRACT

A Variable Offset Positioning Antenna Array for Enhanced Guidance of Automated Guided Vehicles (AGVs) in automated warehousing or storage systems for automobiles or the like, includes two or more inductor coils producing output as a result of interaction with a guidance wire located in or near the surface of the floor which is energized by a frequency generator, and an on board programmable microprocessor which processes the coil output to determine an exact position of the antenna array relative to the guidance wire. In one embodiment, the antenna array enables an AGV to follow a guidance wire at an offset to the direction of travel in order to allow automated storage and retrieval systems to handle asymmetrical items, such as automobiles, more efficiently and cost effectively by decreasing the building space required for travel aisles, vertical conveyors and storage locations as well as decreasing total individual item processing time.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Application 61/145,543,filed Jan. 17, 2009, U.S. Application 61/248,448, filed Oct. 3, 2009,and U.S. Application 61/258,006, filed Nov. 4, 2009, the contents ofeach of which are incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to the guidance and control of anautomated guided vehicle (hereinafter AGV) generally, and moreparticularly, in one embodiment, to a system that enables an AGV totransport both regularly and irregularly shaped loads between a storagelocation and an access location by assuming an offset position relativeto a guidance system such as, for example, an in-ground guidance wire.

BACKGROUND

Conventional parking garages are transforming the landscape to meet thedemand for high capacity storage. In urban centers, where space aboveand below ground is at a premium, the owner of a parking facility isconstrained by a fixed footprint and a certain amount of vertical spaceextending from such footprint. Multi-level garages can only extend sohigh without becoming an eyesore or unwieldy to navigate. Furthermore,self-park and/or attendant-park locations must account for extra spaceon either side of a vehicle for human access to and around the vehicles.

In addition, each storage location has an associated amount of overheadthat must be accommodated by the facility owner. For example, mostfacilities usually allow more than adequate space in front of eachstorage location to allow for typical ingress and egress. Also providedare typical human amenities such as hallways, stairways, elevators, fireescapes, appropriate lighting, and possibly vending machines, bathrooms,office space for onsite personnel, security gates, cameras, alarmsystems, and the like. Self park facilities also frequently promoteaccidental contact between cars due to driver error, and createopportunities for thieves, vandals and other undesirables. Accordingly,for each storage location at a given site, there is an associated amountof extra space necessary to accommodate user access and traffic, as wellas an associated amount of additional resources for human amenities,security and the like.

The required level of overhead limits the number of vehicles that can bestored at a site and adds considerably to the cost of operating aparking facility. There is a need, therefore, for an automated storagesystem that overcomes the need for human-related overhead, that isefficient to construct and operate, and that does not require additionalspace or property necessary to accommodate sporadic human access.

Existing and established methods of maneuvering an AGV along an in-floorguidance wire use either a single antenna precisely centered on thefront of the AGV, or a pair of antennas precisely centered on the frontand rear of the AGV relative to the direction of travel. ConventionalAGV guidance systems use only the antenna currently leading the AGV, orthe “front” antenna based upon the AGV's direction of travel, to followthe in-floor guidance wire. The trailing or “rear” antenna on an AGVequipped with two antennas is inactive until the AGV reverses direction,at which point the rear antenna effectively becomes the “front” antennaand takes over the AGV system guidance responsibilities. The in-floorguidance wire is laid out in a loop connected to, and energized by, afrequency generator, which transmits an alternating current frequencythrough the guidance wire. Each guidance antenna for the AGV containstwo inductor coils, which individually generate an output voltage basedupon the coil's proximity to the magnetic field generated by thefrequency carrying guidance wire. By balancing the relative strength ofthe signal output from each of the two inductor coils on the frontantenna, and subtracting the strength of the output from one coil fromthe strength of the output from the other coil, and then adjusting thesteering of the AGV to target the point where the “subtractive output”from both coils is equal to zero, the control system of the AGVdynamically adjusts the steering of the AGV to keep the center of theantenna, and therefore the center line of the AGV relative to thedirection of travel, approximately centered over the in-floor guidancewire. Often these systems deploy guidance wires in a grid fashion, withone set of wires effectively forming an “X axis” and another forming a“Y axis” to allow AGVs to maneuver in two directions along the wire gridby turning to follow different axis wires and travelling in differentdirections along the different grid axes. At other times theseconventional systems use a gradually curving wire with a fairly largeturn radius to allow the AGV to follow a single wire to travel in analternate direction.

There are three common problems/limitations of existing AGV guidancesystems:

-   -   1) When the AGV travels to a position where either outer edge of        an antenna inductor coil suddenly passes beyond the vertical        plane of the in-floor guidance wire, the antenna produces a        signal which is the same regardless of which side of the wire        the antenna is on. Because the system is unable to positively        identify which direction of travel is required to re-acquire the        guidance wire, an “off wire” alarm condition usually occurs that        stops the AGV and requires human intervention to return the AGV        to the guidance wire and reactivate it. Alternately, the AGV can        follow a limited search pattern to find the guidance wire, but        with the risk of searching too far in the wrong direction and        becoming further lost and/or risking a possible collision with        objects outside the normal AGV travel lane.    -   2) The “centered only” travel path greatly limits the ability of        AGV systems to efficiently process and transport asymmetrically        proportioned items, and with the result that AGV systems are        primarily implemented to handle items which have very limited,        or at least very predictable, variations in size and shape.    -   3) The “subtractive output” analysis of the coil signal has some        weakness and reliability issues which can cause guidance system        problems if there are variations throughout the course of travel        in the distance between the antennas and guidance wire or other        items which impact the relative strength of the magnetic field        generated by the guidance wire signal.

SUMMARY

One embodiment of the present invention uses substantially similarin-floor guidance wire systems with significantly different antennas andinductor coil configurations, and processes the output from the inductorcoils through an onboard programmable microprocessor which analyzes therelative strength of signal output of one or more inductor coils as aratio of the total strength of signal output currently detected by allcoils, or a selection of other adjacent coils, to determine the preciseposition of the antenna, and therefore the AGV, relative to the guidancewire, rather than merely targeting a “subtractive output” valueapproaching zero.

The present system employs significant advances in guidance controlmethodology that more efficiently uses an in floor wire based guidancesystem. Instead of a dynamic steering system that always attempts toguide the AGV to a position where the output from two coils isapproximately balanced, resulting in the AGV always being approximatelycentered relative to its direction of travel over the guidance wire, theguidance system of the invention can purposefully shift the AGV to trackat a specific and dynamically variable offset distance relative to theguidance wire by following the wire at any point within the outercumulative boundary of an array of two or more inductor coils. This isaccomplished by directing the AGV to follow a specific output reading,which equals a numeric expression of an exact position relative to thein-floor guidance wire, based upon an analysis of the relative strengthsof the output from two or more inductor coils. This allows the AGV todeliberately follow an “offset track” in which the center line of theAGV in respect to direction of travel varies as needed and specifiedrelative to the position in the floor of the guidance wire.

An advantage of this “offset track” system is that it enables an AGV totransport asymmetrically shaped items, such as automobiles, which mayhave a different front overhang (center of front wheel to farthest frontextension of the automobile) versus rear overhang (center of rear wheelto farthest rear extension of the automobile) sideways down a transportaisle without significantly expanding the transport aisle's total widthrelative to the total overall length of the automobile being carried. Byshifting the AGV to one side or the other of the guidance wire tocompensate for the asymmetrical aspect of the load being carried, theAGV can travel down an aisle approximately the same size as the maximumwidth of the load while still following a single stationary guidancewire permanently located in the middle of the transport aisle.

Furthermore, the guidance technology of the present inventionincorporates more than two inductor coils into a single antenna, formingin those instances an extended antenna array. In this configuration theprogrammable microprocessor assigns a distinct relative value to eachpoint along the extended antenna array. The AGV guidance system can thenbe directed to follow the guidance wire at any specific point along theentire length of the array, increasing the amount and specificity ofobtainable offset relative to the in-floor guidance wire and/or thecenter line relative to the direction of travel of the AGV, from severalinches, to several feet or more up to the entire length of the antennaarray as needed. This allows the total building footprint required fortravel lanes and/or storage locations within a structure designed forthe storage, transport and retrieval of items which may have anasymmetrical aspect to be significantly decreased at considerablesavings in construction, maintenance and real estate related costs.

The manner in which the microprocessor analyzes the output signal fromthe array of inductor coils enables an AGV guidance control system toaffirmatively know which side of the in-floor guidance wire it haspassed in the event that an AGV antenna should move so far to one sidethat the outer most coil extends beyond the in-floor guidance wire. AnAGV so equipped can correct its course back toward the in-floor guidancewire until the antenna again detects its presence without the need toimmediately experience an off-wire shut down and human intervention.

The use of onboard programmable microprocessor ratio analysis alsoallows the AGV guidance system to better compensate for variations inwire depth or signal strength without the need for precision of guidancewire installation or the guidance problems which can occur inconventional wire guidance systems.

The onboard programmable microprocessor combined with other AGV steeringand guidance control system innovations incorporated in aspects of thepresent invention enable the front and rear antennas of an AGV equippedwith two antennas per direction of travel, to be used simultaneously forsteering and control. Such a two antenna guidance system gathers andprocesses information from both the front and rear antenna on a singleAGV to provide a more accurate steering and tracking system and toenable an AGV to perform more complex and exact maneuvers inapplications requiring very exact steering. This ability can also beused to provide a steering and control system with increased amounts offeedback from the additional active antenna sensor to verify correcthandling, steering, tracking, and drive performance is being realized bythe AGV so equipped.

The expanded sensing range and precision with which location relative toa guidance wire can be determined by the antenna array, in accordancewith aspects of the present invention, enables another previouslyunavailable method of following a grid of guidance wires. This isfacilitated by mounting four or more antenna arrays on each AGV, forinstance one on each side of a roughly rectangular AGV (here referred toas front, back, left side and right side, though an AGV may not actuallybe limited to assignment of only those four specific directions). Whileactively travelling in either direction along one guidance wire (calledan “X axis” wire in this example), either the front antenna array orboth antenna arrays (i.e. the front and rear arrays) will be followingthe guidance wire at any offset amount which may be specified. The otherone or two antenna arrays (in this example referred to as left andright) can simultaneously detect any “Y axis” wires as they are crossedto determine current approximate position of an AGV relative to itsdirection of travel. In certain situations the relative position andchange in relative position of these cross wires as compared to themoving AGV could be used to calculate or confirm in comparison to othersystem indicators the position, heading, and speed of travel of an AGV.When an AGV approaches a “Y axis” wire that is to be followed, the two“side antennas” will detect the presence of that wire as soon as itenters into the sensing range of the side antenna arrays. Using theoutput of the microprocessor aboard the antenna arrays, the AGV isdirected to slow and stop relative to a newly acquired “Y axis” guidancewire at the exact location, including offset if any as required, andthen safely follow the “Y axis” wire based upon the potential asymmetryof its load. At this point all four antenna arrays are positivelysensing an exact location relative to both the “X” and “Y” axes ensuringthe AGV and load are properly positioned. An AGV with multidirectionaltravel capability then immediately begins to proceed down the “Y” axis,without having to execute a turning maneuver, with the previous frontand rear antennas effectively becoming side antennas sensing crossinggrid wires, and the previous side antennas becoming front and rearguidance antennas. This enables a potential decrease in total transitand load processing time and improved system efficiency because thedirection of an AGV can be changed without having to allow for a widerturn radius at corners or provide for additional space in travel aislesto accommodate asymmetrical loads. This capability also decreases costsassociated with storage system footprint, construction and maintenance.

The greater precision and flexibility of the invention's microprocessorequipped antenna array, combined with the enhanced control system of theinvention, the ability to coordinate or confirm positioning through thesimultaneous use of multiple antennas, and methodology for enabling anAGV to transport a load with asymmetrical physical characteristics willallow previously impossible transport and storage operations to occur ina very efficient manner. For example, an asymmetrical load, in this casean automobile, which is driven forward into a system loading area, canbe acquired by an AGV and brought into the system, then transportedsideways or perpendicular to the direction of travel down a travel laneat an offset, and then turned 180 degrees so that upon retrieval it canlater be driven forward out of the system. Upon departure, and due tothe previously described 180 degree turn, the AGV will travel at anopposite offset relative to the retrieval lane. This adjustment canoccur automatically, and the “new” offset orientation can be used by theAGV to transfer the load down other travel lanes, on to and off ofvertical conveyors, and into storage spaces or loading areas as neededto complete the desired storage and retrieval operations.

Thus there is provided an automated storage system for vehicles or thelike that is provided with a guidance system that interacts with aremote-controlled transport system that transports a vehicle between anaccess location, such as a drive-up location, and a storage location.More particularly, in one embodiment, omni-directional, battery-powered,wirelessly-controlled AGVs are provided with a positioning and guidancesystem that allows their travel paths to be shifted relative to anin-floor guidance wire by incorporating antenna arrays composed of twoor more inductor coils and a programmable microprocessor which assigns adistinct value to each position within the length of the array, and acontrol system methodology that the AGV uses to offset its guidance pathrelative to the in-floor guidance wire. Also provided is an AGV guidancecontrol system which affirmatively knows which side of the antenna haspassed beyond an in-floor guidance wire in the event that an “off-wire”condition occurs that could enable an AGV to reliably correct back to aposition over the in-floor guidance wire without a guidance system shutdown and human intervention. Aspects of the present guidance system arebetter able to compensate for variations in wire depth or signalstrength than conventional wire guidance systems and provide an AGVpossessing multidirectional travel capability with a more efficient modeof maneuvering, which can increase system efficiency and decrease costsassociated with storage system footprint, construction and maintenance.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a conventional two-antenna AGV oriented to anin-floor guidance wire.

FIG. 2A is an elevational view and FIG. 2B is a plan view of the AGVantenna of FIG. 1.

FIG. 3 is one embodiment of an enhanced AGV including a plurality ofvariable offset positioning antenna arrays of the present invention.

FIG. 4 (FIGS. 4A-4F) illustrate elevation and plan views of one antennafrom FIG. 3 showing a two coil version with a programmable onboardmicroprocessor enabling an AGV to track at an offset relative to anin-floor guidance wire.

FIG. 5 (FIGS. 5A-5C) illustrates one embodiment of a multiple coilantenna with a programmable onboard microprocessor in various centeredand offset positions relative to the in-floor guidance wire.

FIG. 6 (FIGS. 6A-6C) illustrates one embodiment of a control methodincorporating the multiple coil antenna of FIG. 5.

FIG. 7 illustrates one embodiment of an enhanced AGV having two variableoffset positioning antenna arrays and various offset positioningrelative to a guide wire.

FIG. 8 (FIGS. 8A-8B) illustrates one embodiment of an enhanced AGVhaving four variable offset positioning antenna arrays and variousoffset positioning relative to X-axis and Y-axis in-ground guide wires.

FIG. 9 demonstrates one embodiment of an AGV that acquires anoff-centered load, the AGV being capable of traveling at an offset to acentral guidance wire.

FIG. 10 demonstrates one embodiment of an AGV traveling at an offset toa central guidance wire enabling it to traverse around an obstacleblocking a travel aisle.

FIG. 11 demonstrates a comparison of a conventional AGV with oneembodiment of an AGV of the present invention showing the utilization ofa narrower travel lane for the AGV of the present invention.

FIG. 12 demonstrates another comparison of a conventional AGV with oneembodiment of an AGV of the present invention demonstrating theadvantage of the AGV of the present invention and using its controlmethod to being able to transport asymmetrical items which might be longand narrow by following one wire axis down a travel lane that is wideenough to accommodate the length of the item, then shifting sideways andfollowing a different wire axis into narrower storage lanes and/orstorage racks without having to allow for room to turn the AGV or theload into the storage aisles.

FIG. 13 demonstrates one embodiment of the use of an AGV of the presentinvention to transport and re-orient a load between a loading area and astorage area.

FIG. 14A is a schematic view of one embodiment of a control system for afacility utilizing the enhanced AGV of the present invention.

FIG. 14B is a diagram of one embodiment of a control system constructedin accordance with the invention.

FIG. 14C is an exemplary and non-limiting block diagram of a controlsystem in accordance with an embodiment of the invention.

FIG. 15 illustrates one embodiment of a facility for use with anembodiment of the AGV of the present invention having storagearrangements and travel paths.

FIG. 16 illustrates various storage solutions for a load carried by anAGV of the present invention.

FIGS. 17A-17D illustrate one embodiment of a control method and use ofan AGV to acquire a load from a storage location.

FIGS. 18A-18C illustrate one embodiment of a control method and use ofan AGV to re-route a travel path around an obstruction.

FIGS. 19A-19D illustrate one embodiment of a control method and the useof multiple AGVs to retrieve a load from a blocked storage location.

FIG. 20 is a flowchart describing the process for computing the positionvalue as performed by the microprocessor in accordance with anembodiment of the invention.

FIG. 21 is a top view of an alternative embodiment of an AGV inaccordance with the present invention.

FIG. 22 illustrates one embodiment of the AGV of the invention carryinga vehicle tray.

FIG. 23 is one embodiment of an edge view of FIG. 22.

FIG. 24 illustrates one embodiment of an AGV of the invention carrying astorage locker.

FIG. 25 is one embodiment of an edge view of FIG. 24.

FIG. 26 illustrates an alternative embodiment of an AGV of the inventiontraveling along a diagonal path.

DESCRIPTION OF PREFERRED EMBODIMENTS

This disclosure describes the best mode or modes of practicing theinvention as presently contemplated. This description is not intended tobe understood in a limiting sense, but provides an example of theinvention presented solely for illustrative purposes by reference to theaccompanying drawings to advise one of ordinary skill in the art of theadvantages and construction of the invention. In the various views ofthe drawings, like reference characters designate like or similar parts.

FIG. 1 is a diagrammatic view of one example of a conventional AGV 50centered over an in-floor guide wire system having an “X”-axis guidewire 70 and a “Y”-axis guide wire 75. Conventional AGV systems are oftendeployed in a grid of X-axis and Y-axis wires to allow AGVs to performtwo-dimensional travel maneuvers along the grid by turning to followdifferent axis wires and travelling in different directions along thedifferent grid axes. At other times these systems use a graduallycurving wire with a fairly large turn radius to allow the AGV to followa single wire to travel in an alternate direction (see FIG. 12 forexample). As discussed herein, the X and Y directions are generallyorthogonal and understood with reference to a plan or top view, i.e.looking down on the AGV where the X direction designates horizontalmovement and the Y direction designates vertical movement along a floorlayout, although it is also understood that the X and Y directions arerelative and are designated herein for purposes of convenience and forease in understanding the relative positioning of the AGV and itsenvironment.

In the embodiment of FIG. 1, the conventional AGV 50 has a front antenna60 and a rear antenna 65 and is centered over guidance wires 70 and 75.Existing and established methods of maneuvering an AGV along an in-floorguidance wire utilize either a single antenna precisely centered on thefront of the AGV (antenna 60 in FIG. 1), or a pair of antennas (antennas60 and 65 in FIG. 1) precisely centered on the front and rear of the AGV(50 in FIG. 1) relative to the direction of travel D as shown in FIG. 1.Conventional AGV guidance systems use only the antenna currently leadingthe AGV, or the front antenna based upon the AGV's current direction oftravel, to follow the in-floor guidance wire. The trailing or rearantenna is generally inactive until the AGV reverses direction, at whichpoint it becomes the front antenna and takes over the AGV systemguidance responsibilities.

FIG. 2A is an elevation and FIG. 2B is a plan view of the front antenna60 of FIG. 1. The antenna 60 contains two inductor coils 62 and 64,which individually generate an output voltage based upon their proximityto the magnetic field of the frequency carrying guide wire 70. Thein-floor guidance wire (70, 75) is generally laid out in a loop (seeloops 920 and 930 in FIG. 14A for example) connected to, and energizedby, a frequency generator (see frequency generators 925 and 935 in FIG.14A for example), which transmits an alternating current frequencythrough the guide wire. By balancing the relative strength of the signaloutput from each of these two inductor coils 62, 64 on the antenna 70,and subtracting the strength of the output from one coil from thestrength of the output from the other coil, and then adjusting thesteering of the AGV 50 to target the point where the subtractive outputfrom both coils is equal to zero, the control system (not shown) of theAGV 50 dynamically adjusts the steering of the AGV 50 to keep the centerof the antenna 60, and therefore the center line of the AGV 50 relativeto the direction of travel, approximately centered over the in-floorguidance wire 70.

However, as noted previously, conventional AGV systems have manydrawbacks that limit the ability of the AGV to react to unexpectedtravel conditions, such as blockages in a travel lane, or to performoperations that require the AGV to position in an offset conditionrelative to a guidance wire system. The two antennas, two coil systemdescribed in FIGS. 1-2B limits a conventional AGV's travel to a centeredposition relative to a guidance system, which results in an inefficientsystem as compared with the AGV array and control method of the presentinvention.

FIG. 3 illustrates one embodiment of an AGV 100 of the present inventioncentered over an in-floor mounted guide wire system having an “X”-axisguide wire 70 and a “Y”-axis guide wire 75, it being understood that theguidance system as a whole is preferably comprised of a network ormatrix of guide wires attached to a central control system (see FIGS.14A and 14B). The AGV 100 further comprises a plurality of antennas 110,120, 130, and 140 that are designated for purposes of easy reference asfront antenna 110, rear antenna 120, upper antenna 130, and lowerantenna 140. As will be described in greater detail below, thearrangement of antennas aligned along both the X- and Y-axes providesone aspect for greater flexibility in movement and guidance of the AGV100 relative to the guide wire network.

FIGS. 4A-4F illustrate one embodiment of one of the enhanced antennaarrays of FIG. 3, which for purposes of explanation will be referred toas antenna 110 or the front antenna 110 from FIG. 3. FIGS. 4A, 4C and 4Eare elevations and FIGS. 4B, 4D and 4F are plan views of antenna 110.However, it will be appreciated that the same configuration could beapplied to each antenna on AGV 100. The antenna 110 of the embodiment ofFIGS. 4A-4F further comprises a plurality of inductor coils 112 and 114and a programmable onboard microprocessor 116 enabling the AGV 100 totravel at an offset relative to the in-floor guidance wire 70. Whileonly two inductor coils 112 and 114 are shown, more than two inductorcoils are contemplated as will be described below. Inductor coils 112and 114 in the antenna 110 generate an output voltage as in aconventional AGV antenna, and are used to keep the AGV 100 centered overthe guidance wire 70 when desirable. In one embodiment, the onboardprogrammable microprocessor 116 receives and performs a mathematicalanalysis of the inductor coil output currents, then produces a newoutput signal of its own. This enables the AGV 100 (FIG. 3) to travelwith its antennas 110, 120, 130 and 140 centered over the guidance wire70 as shown in FIGS. 4A and 4B, or intentionally shift a controllableand variable distance to either side of the guidance wire 70 as shown inFIGS. 4C through 4F, while still reliably following the guidance wires.This offset from the center line could extend up to, and slightlybeyond, the width 118 (FIG. 4A) of the antenna array 110 if desired.

FIGS. 5A through 5C illustrate elevation views of an alternativeembodiment of an antenna array 210 for use with an AGV 100 that ispositioned relative to a guide wire 70. Antenna 210 further comprises aplurality of inductor coils 220, 230, 240, 250, 260 and 270 positionedrelative to a center line 212 of the antenna 210, and an onboardprogrammable microprocessor 280. In one aspect, the onboard programmablemicroprocessor 280 analyzes the output from the array of inductor coils220-270 to keep an AGV centered over an in-floor guidance wire 70 whenthat is desirable as shown in FIG. 5A. Alternatively, the onboardprogrammable microprocessor 280 can allow an AGV equipped with anantenna 210 to intentionally and precisely follow a course shifted offof the center line 212 relative to the guide wire 70 as shown in FIGS.5B and 5C. The plurality of inductor coils 220-270 coupled with theonboard programmable microprocessor 280 allows an AGV to seamlesslyshift its location over the guidance wire 70 to any position along thelength of the array of inductor coils so as to shift the center line 212of the AGV a precisely controllable amount in relation to the guidancewire 70, far beyond the distance at which a conventional AGV guidanceantenna would be able to detect the magnetic field produced by thefrequency carried through the guidance wire 70.

In one embodiment of the invention, the antenna array 200 is capable ofsensing multiple frequencies simultaneously of a single guidance wire 70or multiple guidance wires. When multiple frequencies are utilized thesystem control computer instructs the AGV to select the desiredfrequency. In accordance with another embodiment of the inventionmultiple guidance wires can be utilized. The wires may be operable at asingle frequency or each wire may have a different frequency.

In accordance with the principles of the invention, the onboardprogrammable microprocessor 280 analyzes the outputs of the inductorcoils 220-270 in the antenna array 210 and assigns a value to each pointalong the array relative to the output generated by each of theindividual inductor coils. Each of coils 220-270 has a unique indexnumber and it outputs an alternating current (AC) that is a function ofthe proximity of the coil to the guidance wire 70 and the currentmagnitude in the wire 70. The output of each coil is processed by anelectric circuit (not shown) adapted to generate a digital signal thatcan be analyzed by the microprocessor 280. In an exemplary embodiment,this can be achieved by rectification of the AC signal to produce a DCsignal, and then converting the DC signal into a digital signal using anA/D convertor.

The microprocessor 280 generates a position value representing thelocation of the antenna 210 relative to the guidance wire 70. Theposition value is determined based on a pair of coils 220-270 having thestrongest signals. This approach reduces the dependency in theelectromagnetic field of the guidance wire 70.

FIG. 20 shows an exemplary and non-limiting flowchart 1500 describingthe process for computing the position value as performed by themicroprocessor 280 in accordance with an embodiment of the invention. AtS1510, digital signals corresponding to the output signals of each coil220-270 are received and recorded by the microprocessor 280. Each coil'scurrent is preferably sampled by an A/D at ˜1000 times per second(although other sampling rates are contemplated), where the coil outputis related to the proximity of the coil to the guide wire and currentmagnitude in the wire, and where each coil can be individuallyidentified such that the microprocessor knows which signal is from whichcoil. At S1520, two of the recorded signals having the largest value aredetermined. These signals will be referred hereinafter as Va and Vb andthe indexes of the coil producing signals Va and Vb will be referred toas Ia and Ib respectively. As mentioned above, each of coils 220-270 isassociated with a unique index number. At S1530, it is determinedwhether the signals Va and Vb are from adjacent coils. If so, executioncontinues to S1550. If it is determined that signals Va and Vb are notfrom adjacent coils, the validity of such signal is checked at S1540 todetermine whether the maximum signal, out of Va and Vb, is below apredefined threshold. If S1540 results with a negative answer, executionterminates; otherwise, execution continues to S1550.

At S1550, a CoilPair parameter is set to a value of the minimum of theindexes Ia and Ib of the coils. For example, if coil 240 and coil 250are determined to be Ia and Ib, then the CoilPair parameter is set to240. At S1560, an Offset value is computed by multiplying a coilseparation distance (d) value by the CoilPair parameter, i.e.,Offset=d*CoilPair. At S1570, the relative position (RelPos) between theselected pair of coils is computed by multiplying the coil separationdistance (d) by a SignalPercentage value, i.e.,RelPos=d*SignalPercentage. The SignalPercentage is the ratio between themaximum signal, out of Va and Vb, and the sum of the signals Va+Vb. Thecoil separation distance (d) is the distance between the coils 220-270.At S1580 a determination is made whether the index Ia is larger than theindex Ib. If so, at S1590 the position is computed as follows:Position=Offset−d/2+RelPos.If it is determined at S1580 that index Ia is not larger than index Ib,the Position is computed at S1595 using the following equation:Position=Offset+d/2+RelPos.

FIG. 6A-6C illustrate one embodiment of an analysis used to determinethe relative positioning of an antenna 210 as shown in FIGS. 5A-5C fromthe center line 212 and the guide wire 70. The onboard programmablemicroprocessor 280 analyzes output from multiple inductor coils 220-270in the antenna array and assigns a value to each point along the arrayrelative to the output generated by each of the individual inductorcoils. In the example shown in FIGS. 6A-6C, the centered relationshipbetween the antenna array and the guidance wire 70 would produce a valueof ˜245 (i.e. centered between coils 240 and 250), though actual outputnumbering range could vary based upon the application or control systemused. If an AGV travels off of the guidance wire 70 too far to the rightfor example, the analysis of the onboard programmable microprocessor 280would so indicate and output a corresponding value or other appropriateform of communication signal to the AGV control system. In the exampleof FIG. 6B, a value of less than 220 indicates to the AGV control systemthat the AGV needs to travel to the left in order to return to acentered position over the guidance wire 70 as shown in FIG. 6A. If anAGV travels off of the guidance wire 70 too far to the left as shown inFIG. 6C, the onboard programmable microprocessor 280 generates an outputwhich is indicative of its position. In the example of FIG. 6C, anyvalue greater than 270 indicates to the AGV control system that the AGVneeds to travel to the right in order to return to its centered positionover the guidance wire 70 as shown in FIG. 6A. The extent to which anAGV may be displaced from a guidance wire 70 or the like will depend ona variety of factors, including but not limited to the frequencystrength of the guidance wire 70, the sensitivity of the inductor coilsand the manner in which such components are associated by the onboardprogrammable microprocessor.

The expanded reach of an antenna array as illustrated in FIGS. 6A-6C,for example, decreases the risk of an AGV experiencing off-wire shutdown situations where the AGV loses control contact with the guidancewire network. AGVs equipped with the enhanced antennas as describedherein have a much larger travel window while still maintaining contactwith the magnetic field created by the in-floor guidance wire network.In addition, upon losing contact with the magnetic field created by theguidance wire, the control system enables a positive indication of whichdirection of travel is required to regain contact with the magneticfield created by the in-floor guidance wire system through the use of anindicator coil positioning value system as illustrated in FIGS. 6A-6Cfor example. Other control systems are contemplated. Thus, an AGVequipped with enhanced antennas and under an appropriate control systemand method could perform maneuvers to return to the guidance wirewithout having to experience an off-wire shut down, which wouldnecessitate human intervention. In addition, while conventional AGVsystems may be designed to avoid travel lane paths and maneuvers thatcould produce an off wire situation, thus limiting some options foroperational efficiencies, the control system and AGV of the presentinvention allows for more complex AGV maneuvers to be routinelyperformed without service interruptions and therefore allows moreefficient operational performance and more efficient use of space.

FIGS. 7 through 8B illustrate two non-limiting embodiments of an AGV 200and 300 illustrating aspects of the present invention, with the AGV 200of FIG. 7 incorporating front and rear antennas 202 and 204 and the AGV300 of FIGS. 8A and 8B incorporating a plurality of antennas 312, 314,316 and 318 along each side of the AGV 300. FIG. 7 illustrates oneembodiment of an AGV 200 positioned relative to a guide wire 70 andutilizing a front antenna 202 and a rear antenna 204 having aconstruction similar to the antenna 210 of FIGS. 5A through 6C includinga plurality of inductor coils and an onboard programmable microprocessor(not specifically show). Thus, when AGV 200 moves along a guide wire 70in the direction of travel indicated by arrow 206, the AGV 200 couldmove from a position 208 a that is centered over the guide wire 70 (see,for example, the antenna of FIG. 5A), to a position 208 b that isslightly offset relative to the wire 70 (see, for example, the antennaof FIG. 5B), to a position that is considerably offset relative to thewire 70 (see, for example, the antenna of FIG. 5C). In the embodiment ofFIG. 7, the AGV 200 can operate with only the front antenna 202providing guidance information, or by using both antennas 202 and 204 toconfirm both the leading and trailing edges of AGV positioning andguidance.

FIGS. 8A and 8B illustrate one embodiment of an AGV 300 positionedrelative to an X-axis guide wire 70 and a plurality of Y-axis guidewires 75 a, 75 b, 75 c and 75 d, the AGV 300 utilizing a plurality ofantennas 312, 314, 316 and 318 along each side 302, 304, 306 and 308respectively of the AGV 300. Each of the antennas 312, 314, 316 and 318preferably has a construction similar to the antenna 210 of FIGS. 5Athrough 6C. FIG. 8A illustrates AGV 300 in a first location 320 centeredover guide wires 70 and 75 a and spaced from a target location 340 ofthe AGV that is offset from both the X-axis guide wire 70 and the Y-axisguide wire 75 d. As will be described below, the offset positioning ofan AGV relative to a guide wire network can occur for a variety ofreasons, such as, for example, if the AGV needs to acquire a load (seeFIG. 9) that is not centrally positioned relative to the guide wirenetwork. FIG. 8B illustrates the movement of the AGV 300 from the firstlocation 320 to an intermediate location 330 and then to the targetlocation 340. Movement along the X-axis guide wire is controlled by theinteraction of the antennas 312 and 316 with the onboard programmablemicroprocessor (not shown) and the AGV control system (not shown), wherethe antennas 312 and 316 shift the position of the AGV 300 relative tothe X-axis guide wire 70. A determination of the positioning of the AGV300 relative to the Y-axis wires 75 a-75 d also guides the AGV 300 fromthe first location 320 to the target location 340 where, for example,the antennas 314 and 318 monitor or count the Y-axis wires 75 b and 75 cpassed to indicate the positioning of the AGV 300 relative to the Y-axisnetwork and to ensure that in the embodiment of FIG. 8B the AGV 300stops along the Y-axis wire 75 d. Thus, FIG. 8B demonstrates oneembodiment of a control method used to allow an AGV 300 to follow aguidance wire 70 in the direction of travel with one pair of antennas312 and 316 while sensing the location of guidance wire cross wires 75a-75 d using another pair of antennas 314 and 314, and utilizing outputfrom both pairs of antennas to determine the AGV's exact location withina grid of guidance wires and travel to an exact position within theguidance wire grid expressed as a specific relationship to the positionof specific X and Y axis guidance wires.

FIGS. 7 through 8B illustrate aspects of the invention of an AGVequipped with two or more pairs of antenna arrays that is capable oftraveling through a storage or travel area equipped with multiple axesof an in-floor guidance wire grid and to follow and track, centered orat variable offsets, multiple axes of wires within the grid to reach anexact target location specified by a control system. The travel path isgenerally dictated by a control system (see FIGS. 14A-14C) which couldinstruct the AGV to follow the grid pattern (i.e. travel so far in the Xdirection, then so far in the Y direction), or to cut across grid linesat an angle as described in connection with FIG. 26 below to arrive atthe designated location by the most efficient or most preferable pathavailable. As will be described below, this is very advantageous in anAGV-based storage or warehousing application where travel lanes andstorage spaces could be dynamically sized, laid out, and assigned basedupon current needs and the size, shape and transfer plan for a specificitem or items to be stored, rather than having to be determined ahead oftime for a limited number of anticipated purposes during the storagesystem design process. This also allows AGV-based storage systems to befar more flexible and accommodating than non AGV-based systems currentlyin use and drastically improve their cost efficiency and longevity ofoperation.

FIG. 9 illustrates one embodiment of an AGV 400 having antennas 410 and420 to travel along a guidance wire 70 to acquire an off-centered load430 (an automobile in this example) within a loading area 440. The AGV400, with control and guidance from other devices, sensors, measuringimplements, or human intervention, could shift from a centered position450 a in relationship to the guidance wire 70 to an offset position 450b in order to approach and acquire the target item 430 along position450 c, which is not situated exactly centered relative to the in-floorguidance wire 70. This aspect could be used to handle irregularly shapeditems or items which were placed imprecisely by imperfect human ormechanical operations. For example, items unloaded into an automatedwarehouse by human workers and not placed exactly on center in a loadingarea could have their exact position detected by sensors within theloading area or communicated by human workers through a human machineinterface system, and an AGV equipped with the antennas and controlsystem of the present invention could shift off center as needed tocorrectly approach and acquire the target item, then shift back oncenter or to an appropriate offset as needed, to transport the acquireditem to the appropriate location within the system. In an automatedparking example, where an AGV is used to acquire an off-center targetvehicle in a loading area, for example, the ability of the AGV to traveloffset to a guidance wire effectively centers the AGV relative to thevehicle it is intended to acquire. Thus, the AGV would then travel intoposition below the target vehicle, lift it for transport, then return asdesired to a position of being centered on the guidance wire, or offsetthe appropriate amount to travel with the automobile on board asindicated by the automobile's distinct characteristics and the preferredpath of travel out of the loading area.

In addition to simply acquiring off-center loads, the ability todynamically shift the position of an AGV relative to the location of theguidance wire is also very beneficial in diminishing disruptions ofoperations due to temporary mechanical failures or obstacles within anAGV system. If a disabled piece of equipment or a temporary obstaclesuch as on oil spill, building damage, repair work, or the like shouldinterfere with or partially block a portion of a travel lane, underconventional methods of operation that section of the travel lane wouldneed to be entirely shut down. However, if remaining space within thetravel lane allows, AGVs equipped with the antenna array and/or controlmethod of embodiments of the present invention could simply be directedto shift as required on the guidance wire when passing this particularpoint in the system as shown in FIG. 10, for example, and continue atleast limited travel operations through that area until the source ofthe obstruction had been removed or repaired. FIG. 10, for example,illustrates an AGV 500 having antennas 510 and 520 and that is centeredover a guidance wire 70 within a travel lane 530 defined by boundaries532 and 534. When the AGV 500 encounters an obstruction 540 along itstravel direction 505, the control system (not shown) in conjunction withthe antennas 510 and/or 520 enable the AGV 500 to dynamically shift itsposition relative to the guidance wire 70 a sufficient amount in orderto clear the obstruction 530 and still remain within the boundaries 532and 534 of the travel lane 530.

FIG. 11 illustrates a comparison between the use of a conventional AGV50 (see also FIG. 1) and the space-saving advantage gained by using oneembodiment of an AGV 600 incorporating an antenna array 610, 620 andcontrol method of the invention when carrying an asymmetrical load 630down a travel lane 640, or onto and off of a conveyor 650, or into astorage location, for example. The ability to dynamically shift theposition of the AGV 600 into an offset position relative to a guidancesystem within a travel lane enables the use of a narrower overall travellane or smaller conveyor system or smaller storage location as the casemay be. In one example of one embodiment, the conventional AGV 50 picksup automobile 630 by lifting under the automobile's tires as describedin connection with U.S. Patent Application 61/145,543, filed Jan. 17,2009, and incorporated herein by reference, carrying the automobile 630sideways down a travel lane 640 (perpendicular to the automobile'snormal forwards/backwards travel orientation) using conventional AGVguidance antenna 60 and 65 (see also FIG. 1), and proceeds along thetravel lane 640 with the guidance wire 70 centered under the AGV 50,which would in turn be centered under the automobile's wheel base. Inone specific example, assume that the largest vehicle to be accommodatedin an automated AGV based parking system is a 1999 General Motors“Suburban” Sports Utility Vehicle. This vehicle is 219.9 inches long,and has a front overhang (center of front wheel to farthest frontextension of the automobile) of 36.2 inches and a rear overhang (centerof rear wheel to farthest rear extension of the automobile) of 52.8inches. In order for the AGV 50 to be able to carry this vehicle 630down the travel lane 640, facing in either direction (i.e. facing“forward” or “backward” within the lane), the minimum allowable spacerequired would be 219.9 inches plus the difference in front and rearoverhangs (16.6 inches), or a total of 236.5 inches plus any requiredclearances for safety factors, and thus the travel lane 640 would have aminimum width defined by boundaries 642 and 644 as shown in FIG. 11.This same additional 16.6 inches of length would need to be added toeach storage space which could accommodate this automobile, and to eachconveyor 650 which would transport it between levels within a parkingstructure. This results in approximately 7.5% more building footprint,mechanical space, building materials, and associated construction coststo accommodate the vehicle 630 within the system than the actual exactphysical size of it would require. However, by using an embodiment ofthe AGV 600 of the present invention to shift the point on the antennaarrays 610, 620 at which the AGV 600 is following the guidance wire 70precisely 8.3 inches of offset towards the rear of this automobile 630,the travel lane 640, storage spaces, and conveyors can be set at theactual maximum automobile size of 219.9 inches, plus any requiredclearances for safety factors, and have a minimum width defined byboundaries 646 and 648. In a large parking structure or automatedwarehouse, 7.5% savings in real estate and construction costs can equalhundreds of thousands of dollars per project.

FIG. 12 illustrates a comparison between the use of a conventional AGV50 (see also FIG. 1) and the space-saving advantage gained by using oneembodiment of an AGV 700 incorporating an antenna array 710, 715, 720and 725 and control method (not shown) when carrying a load 730 that isasymmetrical or long and narrow as shown, for example. As shown on theleft side of FIG. 12, if it is desired to move the load 730 with aconventional AGV 50 from a first position 740 to a second position 750,or from guide wire 70 to 75 a, the AGV 50 must first travel along theguide wire 70 using antennas 60 and 65 until the AGV encounters guidewire 75 a, at which point the AGV 50 must rotate, clockwise in thisexample, along a travel path 745 so that the antennas 60 and 65 canacquire the guide wire 75 a for guidance of the AGV 50 along guide wire75 a. Thus, when switching directions between an X-axis guide wire suchas 70 and a Y-axis guide wire such as 75 a, the travel lane or footprintmust be dimensioned to accommodate the largest dimension of the load 730in both directions as shown. However, as shown on the right side of FIG.12, if it is desired to move the load 730 with an embodiment of the AGV700 of the present invention from a first position 760 to a secondposition 770, or from guide wire 70 to guide wire 75 b, movement alongguide wire 70 toward guide wire 75 b is controlled and guided usingantennas 710 and 720. Upon contact of the AGV 700 with guide wire 75 b,the AGV 700 shifts direction along guide wire 75 b with antennas 715 and725 assuming guidance and control of the AGV 700 along guide wire 75 b.The AGV 700 may utilize an omnidirectional drive and steering mechanismas set forth in U.S. Application 61/248,448, filed Oct. 3, 2009,incorporated herein by reference herein, to shift the direction ofmovement of the AGV 700 between axes 70, 75 b without altering theposition of the load 730 as required with the conventional AGV 50 asshown on the left side of FIG. 12. Thus, movement of the same load 730with the enhanced AGV 700 from an X-axis direction to a Y-axis directionrequires a much smaller travel lane 765 and a much more compact travelfootprint that need only be dimensioned to accommodate the smallestdimension of the load 730 or of the AGV 700, without having to allow forroom to turn the AGV 700 or load 730 and without necessarily requiring,nor precluding, the use of other forms of sensors to confirm the AGV'sphysical location at the junction of the guide wires 70 and 75 b forexample.

FIGS. 13-19D illustrate non-limiting embodiments of an AGV in anautomated storage facility of the type that stores automobiles or thelike. In one example, an automated parking facility includes loadingareas for drop-off and pick-up of vehicles by customers and storageareas for such vehicles that are preferably routinely accessed only byAGVs or the like. While a parking facility is shown and described forpurposes of convenience, it will be appreciated that the embodiments ofthe AGV guidance and control system of the present invention could beused to transport any type of load from a first position to a secondposition along a variety of travel lanes under the control and guidanceof a control system and network of control means such as structural,in-floor guidance systems and/or wireless systems or combinations of thesame. Other control means are contemplated. The system of the presentinvention enables more efficient use of space overall and in particularin the manner of travel throughout the system footprint, with respect toboundaries and obstructions, and in the positioning, placement andaccess of storage positions. The omnidirectional movement of the AGVcombined with the enhanced antenna array and the ability to dynamicallymove into an offset condition relative to guidance systems wires or thelike creates considerable flexibility in movement and positioning withintravel and storage areas.

FIG. 13 illustrates one embodiment of an AGV 800, having antennas 802,804, 806 and 808, that is used to acquire an asymmetrical item 890, inthis case a vehicle with a different front overhang 892 and rear endoverhang 894, from a loading area 810 and transport the vehicle 890 to astorage area 812 and a particular storage location 820. The AGV 800initially situated along the intersection of guide wires 70 a and 75 atravels along guide wire 75 a under the control and guidance of antennas804 and 808 until it acquires the vehicle 890 in the loading area 810,which vehicle 890 has been driven into the loading area 810 so that thefront overhang 892 faces the storage area 812. The actual acquisition ofthe vehicle 890 by the AGV 800 can be accomplished using a plurality ofgripping arms on the vehicle tires 896 as set forth in U.S. Application61/145,543, filed Jan. 17, 2009, incorporated herein by reference, or bybeing parked upon a vehicle tray which the AGV could then pick up andtransport as discussed, for example, in FIGS. 21-23. The acquisition ofthe vehicle 890 is illustrated by arrow 830 and the return of the AGV800 with vehicle 890 to the guide wire 70 within travel lane 850 isillustrated by arrow 832. All of the antennas 802, 804, 806 and 808preferably cooperate in conjunction with a control method and onboardprogrammable microprocessor during the return of the AGV 800 to theintersection of the guide wires 70 a and 75 a.

Because the AGV 800 in this embodiment is situated relative to thevehicle 890 by the tires 896 of the vehicle 890, the position of the AGV800 may require a particular offset relative to the guide wire 70 a inorder to keep the front and rear overhangs 892 and 894 of the vehicle890 within the boundaries 854 and 858 of the travel lane 850. The travellane 850 is dimensioned to accommodate the width and length of mostvehicles should it be desired to transport a vehicle in eitherorientation. Arrow 834 illustrates the movement of vehicle 890 along thetravel lane 850 using the AGV 800 that is offset downward relative tothe guide wire 70 a with antennas 802 and 806 providing guidance andoffset control of the AGV 800 during movement relative to the guide wire70 a. In the embodiment of FIG. 12, the AGV 800 rotates the vehicle 890within the travel lane 850 along arrows 836 to reverse the orientationof the vehicle 890 relative to the travel lane 850, and to reverse theoffset direction relative to the guide wire 70 s, so that the vehicle890 can be later returned to the loading area 810 and driven out of theloading area 810 in a forward direction. The rotation of the vehicle 890also enables the vehicle 890 to be stored in a front-facing condition.While FIG. 13 illustrates rotation of the vehicle 890 within the storagearea 810, it will be appreciated that rotation can occur in the loadingarea 810 through the use of a turntable (not shown) or the like, oralternatively the rotation need not occur at all if it is not importantduring the storage operation or, for example, if another loading area(not shown) is provided on the opposite side of the storage area 810that allows departure of the vehicle in a forward direction. In anembodiment where rotation occurs within the storage area 810, a controlsystem (not shown) may be utilized to determine the best location forrotation taking into consideration the dimension of the vehicle relativeto the travel lanes and any potential obstructions that would otherwiseprevent rotation in certain areas.

After rotation, the AGV 800 and vehicle 890 continues along the travellane 850 in accordance with arrow 838 using a new offset value relativeto the guide wire 70 a until the AGV 800 reaches guide wire 75 b usingantennas 802, 804, 806 and 808 to verify position and direction of theAGV 800 relative to the guide wires 70 a and 75 b. In the presentembodiment, the AGV 800 then follows guide wire 75 b in accordance witharrow 840 while the antennas 804 and 808 are centered relative to guidewire 75 b until AGV 800 reaches guide wire 70 b. In order toappropriately position vehicle 890 relative to the storage location 820along guide wire 75 c, antennas 802 and 806 must assume an offsetcondition relative to the guide wire 70 b so that movement of the AGV800 in accordance with arrow 842 will result in the desired positioningof the vehicle 890 relative to the guide wires 70 b and 75 c. Theultimate placement of a vehicle 890 within a storage location (820 forexample) can be determined by a variety of factors including, but notlimited to the dimensions of the vehicle, the available space and theavailable travel lanes in and around the storage area 812. Thus, byusing the antenna arrays 802, 804, 806 and 808 and control methodsincluded in this invention (as illustrated in one possible example ofmany possible combinations of motions in FIG. 12), the AGV 800 andvehicle 890 could travel throughout the storage system along a guidancewire grid (see FIGS. 14A-14B) detecting X- and Y-axis wires andfollowing travel lanes centered or offset relative to the guidance wiresas needed until reaching a designated storage location at the correctoffset position relative to and within the storage location to depositthe vehicle for storage. The operation of turning the vehicle couldoccur either on the way to storage or when travelling from storage toexit at the loading area as is most efficient in each system, but withthe ultimate result of the vehicle being able to be driven into thesystem going forward and out of the system going forward, and turned bythe AGV within the system, without having to make all travel lanes,vertical conveyors (not shown) and storage locations large enough to beable to accommodate vehicles with different front and rear end overhangswhen facing in either direction.

FIG. 14A illustrates one embodiment of a system layout 900 including astorage facility 905 having a plurality of storage locations 910, aguidance wire grid formed from X-axis guidance wires 920 energized by anX-axis frequency generator 925 and Y-axis guidance wires 930 energizedby a Y-axis frequency generator 935, a plurality of loading areas 940, avertical conveyor 950 to move between vertically-stacked system levels(not shown), a plurality of AGVs 960, a control system 970 such as a PLCcontrol system in wired and/or wireless communication 972 with AGVs 960and controlling loading areas 940, vertical conveyors 950 and AGVs 960,and a server or some other type of control system 980 providingcoordination, routing and inventory instructions to AGV system throughthe control system 970 or directly to the facility 905. The facility 905is preferably provided with dedicated travel lanes such as, but notlimited to travel lanes 990 and 992, for movement of AGVs 960 andvehicles (not shown) to be transported by AGVs 960 between the loadingareas 940 and the storage locations 910.

FIG. 14B shows an exemplary and non-limiting diagram of an automatedparking system 900 a constructed in accordance with one embodiment ofthe invention. The system 900 a locates and tracks the location of AGVs960 a and guides them to parking or storage locations from an accesslocation using, in the illustrated embodiment, radio frequencyidentification (RFID) and proximity sensing techniques. Specifically, avehicle (not shown) is mounted on an AGV 960 a, which includes aplurality of antenna arrays that, in one embodiment, transmit radiofrequency (RF) signals to a radio modem 908 a. The antenna arrays keepthe AGV 960 a aligned along its path by sensing the position of guidewires 920 a, 930 a in the floor in relation to the antenna arrays of theAGV 960 a. The guide wires 920 a, 930 a may be, for example, a RF wireor magnetic strip. Other guide means are contemplated. The intersectionof two guide wires are referred to, in the embodiment of FIG. 14B, asstorage bays 904 a, each of which may include at least a RFID circuit906 a to determine the overall location of the AGV systems 960 a. Todetermine the overall location of an AGV, an RFID chip may be used ateach storage bay location and along predetermined intervals alongpathways. Using these two sensing systems, the facility owner canprecisely guide and track the location of each AGV 960 a. In the presentembodiment, charge stations are also provided to charge the batteries inthe AGV during times of non-use. Other charging means are contemplated.

RF signals generated by the RFID circuits and/or proximity sensors aretransmitted to one or more radio modems 908 a which output datamodulated in the RF signals to a computing device 970 a. The radiomodems 908 a and the computing device may be connected in a networkestablished using a network switch 955 a. The computing device 970 acoordinates the proper retrieval and parking (storing) of a vehicle orthe like mounted on an AGV 960 a from a storage location to an access orretrieval location, and vice versa. In order to move an AGV 960 a fromone location to another, the computing device 970 a continuouslyprocesses the location information, as transmitted by the antenna arrayand/or RFID circuits, and generates signals that instruct the AGV 960 ato follow a particular direction relative to the wire grid. Thegenerated signals are wirelessly transmitted by the radio modem 908 a toa wireless receiver installed in the AGV 960 a.

In one embodiment of the invention a user can interface with the system900 a through, for example, a graphical user interface (GUI), aninteractive voice response (IVR) interface, a web browser, SMS textmessaging, and the like, enabling the user to access information abouthis/her vehicle, pay for parking and/or other services, check balances,provide retrieval instructions, etc. The user's inputs are processed bythe computing device 970 a. For example, the user may request thathis/her car be ready for pick-up at a certain time. The computing device970 a then executes a process for retrieving the vehicle from itsparking location to an access location to be ready for the user at therequested time. With this aim, the computing device 970 a accesses adatabase (not shown) used to store the parking location of the vehicle,computes a path from the current location to the access location andcommunicates the path for the AGV 960 a to take to retrieve the vehicle.The computing device 970 a also computes the amount due for payments,where payments are made through a payment server (not shown). In oneembodiment of the invention, the computing device 970 a generatescontrol data and statistical reports, and maintenance and notificationalerts. In order to allow continuous operation of the system 900 a andto prevent a single point failure, the system 900 a includes a redundantcomputing device 975 a for backing up the computing device 970 a. Incertain embodiments, uninterruptible power supplies (UPS) devices 978 aand a backup power generator 980 a are also utilized in the system 900a.

FIG. 14C shows an exemplary and non-limiting block diagram of a vehiclecontrol unit (VCU) processor 900 c provided on an AGV (not shown). TheVCU 900 c communicates with a power module 910 c, guidance and positionsensors 920 c, a communications module 930 c adapted to transmit/receivesignals from a computing device (such as device 970 a from FIG. 14B) anda servo module 940 c provided with servo motors 941 c, encoders 942 c,proximity sensors 943 c and amplifiers 944 c adapted to transmit andreceive signals to/from the VCU 900 c and a hardware emergency stop 945c. The guidance and position sensors 920 c further comprises a pluralityof antenna arrays 921 c as described herein, each provided with abandpass filter 922 c, multiple inductor coils 923 c, a microcontroller924 c and an amplifier 925 c, and a RFID location reader 926 c forreading the guide wire system. Also provided is a maintenance panel 950c for access to input ports and the like if it is desired to performmaintenance on or otherwise physically connect with the VCU 900 c. TheVCU 900 c is adapted to process input signals entered through panel 950c and input ports, one example for such input signal being a RESETsignal. The VCU 900 c is further capable of producing safety alerts 960c, for example, such as routine audible or visual warning signals orevent specific alerts based on inputs received from an obstacleavoidance module (not shown).

In one embodiment, the VCU 900 c computes precise heading informationfor an AGV from feedback provided by the antenna arrays and the onboardmicroprocessor. Guide wire and wire cross locations as well as centerpoints of storage locations are previously surveyed and stored in adatabase. The master computer processor uses laser scan data from theretrieval or loading bay to calculate travel offsets based on the offsetof the vehicle from the wheelbase, where Offset=(Xwb−Xv)/2 (where Xwb isthe dimension from the front of the vehicle to the center of thewheelbase, and Xv is the dimension from the front of the vehicle to thecenter of the vehicle). Offsets for guide wires paths, wire crosslocations, and storage locations are determined by observation. Headinginformation is then used to compute vehicle yaw to correct for headingerror. Each steering wheel is directed to an Ackermann angle to achievethe desired yaw. In one embodiment, the traffic master (master computerprocessor) creates a path of waypoints to the desired destination, whereeach waypoint consists of heading (vehicle travel direction), vehicleorientation, and path offset. These commands are preferably communicatedto the AGV over wireless communication.

FIG. 15 illustrates one embodiment of a facility 1000 that comprises aplurality of storage locations 1010 occupied by a plurality of shapes1020 representative of different sized vehicles with varying wheelbasesand front/rear overhangs positioned in storage locations 1010. In theillustrated embodiment, the dashed line rectangles also represent anddefine the maximum possible vehicle size to be stored within a storagelocation 1010. Each storage location 1010 is defined by a portion of anX-axis guidance wire 1030 and a portion of an Y-axis guidance wire 1040that are part of a larger guidance wire network within the facility 1000for the guidance, positioning and movement control of AGVs 1050 withinthe storage locations 1010 and a dedicated travel lane 1060. The AGVs1050 are each preferably equipped with a plurality of antenna arrays1052, 1054, 1056 and 1058 as described above for omnidirectionalmovement that is either centered or offset relative to the guidance wirenetwork. In the illustrated embodiment of FIG. 15, the vehicles 1020 areall centered relative to the X-axis and Y-axis guidance wires 1030 and1040 respectively along their wheel base to form AGV travel lanes 1032and 1042 (only two being shown) centered on the X-axis and Y-axisguidance wires 1030 and 1040 respectively. In a preferred embodiment,the longest dimension of an AGV 1050 when travelling in compact mode(the preferred mode of travel when the AGV is not carrying a vehicle) isshorter than the wheel base of all vehicles 1020 stored along aparticular guide wire 1030 so that the AGV 1050 is capable of scootingunder vehicles 1020 such that its longitudinal axis is oriented alongeither an X-axis guide wire or a Y-axis guide wire. In other words,movement of the AGV 1050 could occur with either the antennas 1052 and1056, or with antenna 1054 and 1058 aligned with the X-axis guidancewire. With ultra-compact vehicles such as Smart™ cars with shortenedwheel bases or the like, or in cases of vehicles with especially lowundercarriage clearances it may be necessary to rotate the AGVs prior toscooting under the vehicles or to limit travel between the wheelbases ofthe vehicles in some portions of the facility.

One benefit of the overall control system of the present invention isthat the structural elements of each vehicle, including size, wheelbase, overhangs and the like are captured by system sensors and utilizedby the control system of the invention to efficiently arrange vehiclesrelative to storage locations and/or other vehicles, and suchinformation is also used for guidance of vehicles within travel lanes1060 and relative to travel lane boundaries, obstructions and the like.Furthermore, the ability of AGVs to scoot under vehicles enables thefacility 1000 to maximize storage location density and minimize thenumber of required travel lanes 1060. Another benefit of the overallsystem is that storage locations can be dynamically arranged andre-arranged depending on the structural dimensions of a vehicle and theavailable space in a particular storage location area. For example,three adjacent storage locations currently allocated to accommodatethree maximum-size vehicles could be dynamically re-designed andre-allocated by the master control system to accommodate more than threesmaller vehicles. Alternatively, a single storage location allocated toaccommodate a single maximum-size vehicle could be dynamicallyre-allocated by the master control computer to accommodate twoultra-compact vehicles front-to-back or end-to-end as desired, forexample. In addition, spaces around structural columns and like could bepopulated with grid wires to provide access to an AGV. Therefore,instead of assigning permanent and dedicated storage locations duringsystem layout and creation, the master control computer can takeadvantage of the enhanced antenna array control and guidance system andwire grid network to dynamically assign spaces and storage locations toaccommodate smaller or fewer objects or objects of varying configurationin real time and to adjust the storage capacities to meet demand asneeded.

FIG. 16 illustrates one example of a facility 1100 that comprises aplurality of storage locations 1110 occupied by a plurality of vehicles1120, X and Y guidance wires 1130 and 1140 respectively, an AGV 1150having antennas 1152, 1154, 1156 and 1158, a plurality of conveyors 1160and 1162, and a dedicated travel lane 1170. The AGV 1150 and vehicle1122, upon exiting conveyor 1160, are able to travel to any of the openstorage locations 1110 a, 1110 b, 1110 c or 1110 d. The ultimatedetermination of where vehicle 1122 is stored may depend of a variety offactors including, but not limited to the anticipated storage time ofthe subject vehicle 1122, anticipated storage times of other vehicles inthe facility, load balancing of vehicles on a floor-by-floor basis, andso on.

FIGS. 17A-17D illustrate one example of a facility 1200 that comprises aplurality of storage locations 1210 occupied by a plurality of vehicles1220, X and Y guidance wires 1230 and 1240 respectively, an AGV 1250having antennas 1252, 1254, 1256 and 1258, a plurality of conveyors 1260and 1262, and a dedicated travel lane 1270 having a plurality ofoverflow locations 1272, 1274, 1276, 1278. FIG. 17B illustrates thestorage of vehicles 1222 and 1226 in overflow locations 1272 and 1276respectively. FIG. 17C illustrates the retrieval of vehicle 1220 a fromstorage location 1210 a, whereby AGV 1250 first picks up vehicle 1226and delivers it to overflow storage location 1278 in accordance witharrow 1280, and then AGV 1250 acquires vehicle 1220 a from storagelocation 1210 a and delivers it to travel lane 1270 in accordance witharrow 1282, and then AGV 1250 delivers vehicle 1220 a to the conveyor1260 in accordance with arrow 1284. FIG. 17D illustrates the retrievalof vehicle 1220 b from storage location 1210 b, whereby AGV 1250 firstpicks up vehicle 1222 and delivers it to the now-empty storage location1210 a in accordance with arrows 1290 and 1292, and then AGV 1250acquires vehicle 1220 b from storage location 1210 b and delivers it totravel lane 1270 in accordance with arrow 1294, and then AGV 1250delivers vehicle 1220 b to the conveyor 1260 in accordance with arrow1296. Of course, in FIG. 17C, AGV 1250 could also first pick up vehicle1226 and deliver it to overflow storage location 1274, and then AGV 1250could acquire vehicle 1220 a from storage location 1210 a and deliver itto travel lane 1270, and then AGV 1250 could deliver vehicle 1220 a tothe conveyor 1262 instead of conveyor 1260. The movement of AGVs andvehicles is controlled by a master control system (not shown) throughany of a variety of possible communication systems though most likely awireless data network with receivers on the AGVs and any other sensorand receiver system employed to implement such control and guidance(see, for example, FIGS. 14B and 14C).

FIGS. 18A-18C illustrate one example of a facility 1300 that comprises aplurality of storage locations 1310 occupied by a plurality of vehicles1320, X and Y guidance wires 1330 and 1340 respectively, AGVs 1350 and1352 and a plurality of travel lanes 1360 and 1362 following X-axis andY-axis guide wires respectively and having temporary overflow locations.In the embodiment of FIGS. 18A-18C, there is a problem with AGV 1352carrying vehicle 1322 such that it creates an impassable obstructionalong travel lane 1362. FIGS. 18A-18C illustrate one method ofdynamically re-routing travel lane 1362 to create a new travel lane 1362a (FIG. 18C). First, in a non-limiting method, it is desired for AGV1350 to deliver vehicle 1320 a from storage location 1310 a to storagelocation 1310 b, whereby AGV 1350 follows path 1380 (FIG. 18A) byscooting under stored vehicle 1320 c until it reaches and acquirestarget vehicle 1320 a, and then delivers vehicle 1320 a along path 1382(FIG. 18B) to target location 1310 b. Then, as shown in FIG. 18C,vehicle 1320 c is delivered from storage location 1310 c to storagelocation 1310 d along path 1384, which frees up storage locations 1310a, 1310 c and 1310 e to form the new travel lane 1362 a. This newtemporary travel lane 1362 a is thus established dynamically by thecontrol system (not shown) for Y axis movement within the system toroute around the temporary obstruction 1352 and 1322 until the problemcausing it can be corrected through remote or onsite remedialintervention. Additional vehicles shown above and below the arrow pointsdefining the travel lane 1362 a could also be moved into temporary oroverflow storage locations one space to the right of their currentlocation in order to extend the “Y” axis Travel Lane if and as needed.

FIGS. 19A-19D demonstrate the ability to dynamically coordinate multipleAGVs to retrieve a target load isolated from travel lanes with improvedAVG guidance and control system using variable offset positioningantennas. Specifically, FIGS. 19A-19D illustrate one example of afacility 1400 that comprises a plurality of storage locations 1410occupied by a plurality of vehicles 1420, X and Y guidance wires 1430and 1440 respectively, AGVs 1450, 1452, 1454 and 1456 and a plurality oftravel lanes 1460 and 1462 following X-axis and Y-axis guide wiresrespectively and having temporary overflow locations. FIG. 19Aillustrates the AGVs in standby positions awaiting commands from thecontrol system (not shown). When it is determined that vehicle 1420 aneeds to be retrieved from storage location 1410 a, an optimal retrievalroute 1480 for vehicle 1420 a is determined and plotted by the controlsystem. As shown in FIGS. 19B and 19C, AGVs 1450, 1452, 1454 and 1456are directed to follow paths 1481, 1482, 1483 and 1484 respectively inorder to acquire vehicles 1420 a, 1420 b, 1420 c and 1420 d respectivelyin storage locations 1410 a, 1410 b, 1410 c and 1410 d respectively. Asshown in FIG. 19D, AGV 1452 moves vehicle 1420 b to empty storagelocation 1420 e, AGV 1454 moves vehicle 1420 c to empty storage location1420 f, and AGV 1456 moves vehicle 1420 d to empty storage location 1420g, whereby a new travel lane 1462 a is formed for the retrieval ofvehicle 1420 a.

FIGS. 21-25 illustrate non-limiting embodiments of analternately-constructed AGV 1600 designed to move either automobilesparked on vehicle trays 1700 or storage lockers 1800 from loading areas(not shown) to storage areas (not shown) and then retrieve them ondemand. The system of the present invention is, in one respect, anevolution of the automated storage system of U.S. application Ser. No.12/032,671, filed Feb. 16, 2008, the contents of which are incorporatedherein by reference, although the present system incorporates acontrollable and guidable AGV whereas the '671 application system doesnot. Unlike the previous embodiments described in the presentapplication, the AGV 1600 comprises a rigid framed rectangular body 1610that does not expand or contract as described, for example, in U.S.Application 61/145,543, filed Jan. 17, 2009, incorporated herein byreference. The AGV 1600 drives under a vehicle tray 1700 or storagelocker 1800 to be acquired which in one of many possible embodiments issitting up on four legs 1710 or 1810, and then lifts the vehicle tray1700 or storage locker 1800 at preferably four contact points 1620 byuse of a hydraulic pump motor and hydraulic lifters 1630. Instead of thetarget vehicles or loads (not shown) being parked on a concrete floor ina loading area as shown, for example, in FIG. 13 herein, the vehiclespull onto the vehicle trays 1700 that are suitably supported by andprovided in the loading areas. The vehicle trays 1700 are preferablyelevated relative to the remainder of the system travel area so that theAGV 1600 does not need to change elevation between the loading area andthe storage area, which is not a concern in the previous embodimentswhere the AGV scoots under the vehicle body for acquisition thereof.

Once the vehicles (or other loads) are on the trays 1700, they aretreated similar in all aspects to vehicles handled in previouslydescribed embodiments, where the vehicle-laden tray becomes the loadthat is delivered by the AGV 1600 from the loading area to the storagearea. The vehicle-laden tray is preferably initially scanned by thecontrol system to determine the exact dimensions of the tray withvehicle, after which an AGV 1600 is dispatched to acquire them wherebythey are then picked up and transported from the loading area, throughretrieval lanes at offsets as appropriate, up or down vertical conveyorsas needed, until they are delivered to a storage location. In theembodiment of FIGS. 21-23, the load or the vehicle always remains on topof the tray 1700 as it is moved through the system rather than beinglifted by its tires and then deposited in a storage location. Just as inpreviously-described embodiments, the AGV 1600 travels across standardfloors and follows a wire guidance grid that is optimized by theimplementation of an enhanced AGV antenna array provided on the AGV 1600as described previously and with actions coordinated by a traffic masterserver system. The AGV 1600 of the current embodiment uses anomni-directional drive and steering system that is preferably larger andbased upon a slewing gear rather than that shown in U.S. Application61/248,448, filed Oct. 3, 2009, the contents of which are incorporatedherein by reference, in order to accommodate larger loads necessitatedthrough the transport of storage containers 1800 or the like. In allother aspects, however, the overall system is substantially similar tothe previously described systems, though not quite as efficient in useof space due to the use of vehicle trays and the height of the trays onlegs, but still having the advantage of being able to store cars ofdifferent lengths in different length spaces and being able to shiftvehicles sideways and perform coordinated retrievals just like thepreviously-described AGV systems. The system using the AGV 1600 has anadvantage of being able to handle higher maximum load weights, so thatlarge vehicles or self-storage lockers 1800 are easily handled by it.Similar to the previously-described AGV systems, the AGV 1600 ispreferably battery powered with in-floor charging stations, useswireless communications, and has four drive wheels 1640.

FIG. 26 illustrates yet another embodiment of an AGV 1700 carrying aload 1710 such as a vehicle and having antenna arrays 1702, 1704, 1706,1708 that demonstrates a “skewed crabbing” technique. In FIGS. 7 through8B, for example, and the majority of the other figures described herein,the travel path is generally dictated by a control system that instructsthe AGV to follow horizontal or vertical paths along an X-Y grid patternwith dynamic offsets as required to meet obstacles or otherenvironmental conditions. FIG. 26 illustrates a diagonal travel pathwithin an X-Y wire grid framework defined by X-axis guide wires 70 a-70e and Y-axis guide wires 75 a-75 d, where the AGV 1700 is positionedsuch that the antennas are simultaneously positioned over multipleX-axis and Y-axis guide wires. Such a positioning of the AGV 1700 wouldbe useful for acquiring loads whose center axes are not just offset fromthe guide wires, but also whose axes are not parallel to them, and forpacking non-rectangular loads more economically. Control and guidance ofthe AGV 1700 is performed by a skewing command from the traffic mastercontrol system to the AGV 1700, which adds a skew angle as an offset tothe current heading to position the front and rear antenna readings tocorrespond to the commanded skew angle from the traffic master controlsystem.

In FIG. 26, each antenna array is preferably constructed to distinguishbetween multiple guide wires at the same time. For example, antenna 1706spans between guide wires 70 b, 75 d and 70 c, while antenna 1708 spansbetween guide wires 70 c and 75 c. In the embodiment of FIG. 14A, forexample, the X-axis guide wires 920 are energized with a certain X-axisfrequency 925, while the Y-axis guide wires 930 are energized with acertain Y-axis frequency 935. In the embodiment of FIG. 26, the AGVantenna arrays can distinguish between multiple X-axis guide wires 70 ofthe same frequency and multiple Y-axis guide wires 75 of the samefrequency as long as the respective guide wires are separated by asufficient distance and as long as the antenna inductor coils aresufficiently arranged and controlled by the master control system todistinguish between the respective guide wires relative to the overallposition of the AGV relative to the guide wire layout. In an alternativeembodiment, each X-axis guide wire and each Y-axis guide wire could beprovided with a distinct frequency that is sensed by the inductor coilsin the antenna arrays so that positioning of the AGV 1700 relative tothe guide wire layout can be focused to a specific inductor coil on aspecific antenna array relative to a specific guide wire within theguide wire layout. Such a system may be preferred depending on thespacing of the guide wires so it is not necessary to discriminatebetween multiple guide wires of the same frequency solely through thespacing of such wires relative to the AGV. In other words, with multipledistinct frequencies, the traffic master control system can dynamicallyand angularly skew and offset the positioning of the AGV 1700 throughthe simultaneous processing of multiple frequencies across multipleantenna arrays and by targeting select guidance and positioning sensorswithin the antenna arrays.

While the present invention has been described at some length and withsome particularity with respect to the several described embodiments, itis not intended that it should be limited to any such particulars orembodiments or any particular embodiment, but it is to be construed withreference to the appended claims so as to provide the broadest possibleinterpretation of such claims in view of the prior art and, therefore,to effectively encompass the intended scope of the invention.Furthermore, the foregoing describes the invention in terms ofembodiments foreseen by the inventor for which an enabling descriptionwas available, notwithstanding that insubstantial modifications of theinvention, not presently foreseen, may nonetheless represent equivalentsthereto.

We claim:
 1. A variable offset positioning antenna array for anautomated guided vehicle (AGV) that is adapted to follow a guide wirehaving a frequency, comprising: a) two or more inductor coils that eachgenerate an output based on a strength of the frequency sensed at eachcoil; and b) a programmable microprocessor that processes the outputfrom each coil to determine a position of the antenna array relative tothe guide wire and uses the determined position to control an offsetrelative to the guide wire in a path followed by the AGV equipped withthe antenna array; c) wherein the offset relative to the guide wire isdynamically adjusted.
 2. The antenna array of claim 1, further adaptedto simultaneously follow multiple guide wires having the same ordiffering frequencies to determine data regarding direction of travel,speed, position, or orientation of the AGV incorporating the antennaarray.
 3. The antenna array of claim 1, further comprising a frontantenna array and a rear antenna array incorporated into the AGV andcontrolled by a control system to simultaneously provide guidanceinformation to an AGV guidance and control system for steering andguidance of the AGV.
 4. The antenna array of claim 1, further comprisinguse of one or more additional pairs of antenna arrays on the AGV todetermine a location of the AGV relative to a multiple-axis guide wiregrid.
 5. The antenna array of claim 1, wherein the microprocessordetermines a position of the AGV relative to the guide wire in anoff-wire situation.
 6. The antenna array of claim 1, further comprisinga control system for enabling the AGV to carry a load in multiple offsetpositions relative to the guide wire and the direction of travel.
 7. Theantenna array of claim 1, wherein the guide wire is either a RF wire ormagnetic strip.
 8. The antenna array of claim 1, wherein the output fromthe inductor coils comprises: a) determining two largest output signalsout of all of the output signals; b) determining indexes of two inductorcoils that output the two largest output signals; c) determining if thetwo inductor coils that output the two largest output signals areadjacent; and d) computing a position value using an offset value, arelative position value between the two inductor coils, and a coilseparation distance.
 9. The antenna array of claim 8, wherein computingthe position value further comprises: a) determining a maximum signalout of the two largest output signals; b) if the index of an inductorcoil that outputs the maximum signal is bigger than the index of anindicator coil that outputs the other largest output signal, theposition value is computed as follows: position value=offset−d/2+RelPos;otherwise the position value is computed as follows: positionvalue=offset+d/2+RelPos, wherein d is the coil separation distance, andRelPos is the relative position value between the two inductor coils.10. The antenna array of claim 9, wherein the offset value is computedby multiplying the coil separation distance by a CoilPair parameter,wherein the CoilPair parameter is set to be a minimum value of theindexes of the two indicator coils.
 11. The antenna array of claim 10,wherein the relative position value is computed by multiplying the coilseparation distance by a SignalPercentage value, wherein theSignalPercentage value is a ratio between the maximum output signal anda sum of the two largest output signals.